Facile one-pot synthesis of a BiOBr/Bi_(2)WO_(6) heterojunction with enhanced visible-light photocatalytic activity for tetracycline degradation

Photocatalytic removal of tetracycline(TC)from the wastewater is of great value in the chemical and environmental engineering field.Here,we introduced a facile one-step method for the synthesis of BiOBr/Bi2WO6 heterojunctions by using cheap CTAB as the Br source.We showed the possibility of our method to fine-tune the content of BiOBr in the produced BiOBr/Bi2WO6 by simply changing the dosage of cetyltrimethylammonium bromide(CTAB),providing a platform for the delicate tuning of the visiblelight absorbance ability of the composites.With a suitable heterojunction structure of BiOBr/Bi2WO6-0.2,it exhibited an ultrarapid photocatalytic activity towards TC(20 mg
L^(-1)),with a competitive removal efficiency of 88.1%within 60 min and an ultrahigh removal rate of 0.0349 min^(-1).It could also be robustly recycled for at least 5 cycles with slight removal efficiency loss.We demonstrated that this exciting photocatalytic performance was due to the highly decreased recombination of photoinduced electrons and holes on our composites by constructing this heterojunction structure,and the resulting
OH and
O^(-)_(2)contributed to the effective degradation of TC to CO_(2).

Facile synthesis of efficient pentaethylenehexamine-phosphotungstic acid heterogeneous catalysts for oxidative desulfurization

The ultra-deep desulfurization of oil needs to be solved urgently due to various problems,including environmental pollution and environmental protection requirements.Oxidative desulfurization(ODS)was considered to be the most promising technology.The facile synthesis of highly efficient and stable HPW-based heterogeneous catalysts for oxidative desulfurization is still a challenging task.In this paper,pentamethylene hexamine(PEHA)and phosphotungstic acid(HPW)were combined by a simple one-step method to prepare a heterogeneous catalyst of PEHA-HPW for the production of ultra-deep desulfurization fuel oil.The composite material exhibited excellent catalytic activity and high recyclability,which could reach a 100% dibenzothiophene(DBT)removal rate in 30 min and be recycled at least 5 times.Experiments and DFT simulations were used to better examine the ODS mechanism of PEHA-HPW.It was proved that the rich amino groups on the surface of PEHA-HPW play a crucial role.This work provides a simple and feasible way for the manufacture of efficient HPW-based catalysts.

Optimization and control of a reactive distillation process for the synthesis of dimethyl carbonate

Dimethyl carbonate is an environmentally benign and biodegradable chemical.Based on integration of reactive distillation and pressure-swing distillation technologies,a novel process for synthesis of dimethyl carbonate through transesterification with propylene carbonate and methanol has been developed by Huang et al.In this work,the optimization of this process was performed by minimizing the total TAC.The results show that the optimal design flowsheet can save energy consumption by 18.6% with the propylene carbonate conversion of 99.9%.Then,an effective plant-wide control structure for the process was developed.Dynamic simulation results demonstrate that the temperature/flow rate cascade control plus with simple temperature control can keep not only product purity but also the conversion of the reactant at their desired values in the face of the disturbance in reactant feed flow rate and feed composition.

Preparation and shaping of solid acid SO_4^(2-)/TiO_2 and its application for esterification of propylene glycol monomethyl ether and acetic acid

The solid acid SO_4^(2-)/TiO_2 was prepared by immersion method and applied for synthesis of propylene glycol methyl ether acetate(PMA) through esterification reaction of propylene glycol monomethyl ether(PM)and acetic acid(HAc). The optimal catalyst preparation condition was determined by orthogonal analysis of parameters in a five-factor and four-level test. The obtained solid acid catalysts were characterized in detail by means of X-ray powder diffraction, thermogravimetry, pyridine adsorbed IR analysis, scanning electron microscopy, and BET surface area method. Synthesis of PMA was studied in this paper through experimental investigation of reaction conditions such as temperature, molar ratio of reactants, catalyst dosage and agitation speed. Based on its possible reaction mechanism, a pseudo-homogeneous kinetic model was established and its activation energies E_a^+ and E_a^-,65.68 × 10~3J·mol^(-1) and 57.78 × 10~3J·mol^(-1), were estimated. To prepare shaped solid acid catalyst SO_4^(2-)/TiO_2, the shaping method of impregnation–shaping–impregnation was applied. The optimal molding formulation of solid acid catalyst, obtained from the orthogonal test, was found to be binder 7 wt%, reinforcing agent 20 wt%, pore forming material 2.5 wt%, and lubricant 4 wt%.The results of performance test of catalyst demonstrated that the shaped solid acid catalyst exhibited high activity and stability.

Polymeric ionic liquids(PILs)with high acid density:Tunable catalytic performance for biodiesel production

A series of polymeric ionic liquids(PILs)used as effective heterogeneous catalysts for biodiesel production via esterification of free fatty acids(FFAs)were effectively prepared by the reaction of poly(ethylene imine)(PEI)polymers with different molecular weight and 1,3-propanesultone,followed by the further acidification with differential effective acids,i.e.H2SO4,CF3SO3H,CH3SO3H or p-toluenesulfonic acid(p-TSA).Ultrahigh acidity and catalytic performance were achieved and could be fine-tuned by simply adjusting the molecular weight of PEI and by further treatment of acids.Specifically,under the optimal conditions(i.e.reaction temperature was 70℃,reaction time was 2.0 h,catalyst dosage was 3.15%(mass),and alcohol/acid molar ratio was 14:1)acquired through the Box-BEHNKEN response surface methodology,a high oleic acid conversion of 98.42%could be obtained over the optimal PIL,PEI(70000)-PS-p-TSA.Additionally,our PILs also showed high generality for esterification of other FFAs,with general high conversion over 90%noted in each case even under much milder reaction conditions compared to other conventional catalysts.

Novel multi–SO_(3)H functionalized ionic liquids as highly efficient catalyst for synthesis of biodiesel

Biodiesel is an attractive alternative to fossil fuels due to the energy and environmental concerns. In this paper, seven different multi –SO_(3)H functionalized ILs based on the low-cost less-substituted amines, which contained massive sites for functionalization of sulfonic acid groups and further treatment of sulfonate-based anions, were prepared as catalysts with high acidity and desirable catalytic activity for the synthesis of biodiesel from the esterification of oleic acid with methanol. The physicochemical properties of these acidic ILs were characterized by a variety of analytical techniques such as FT-IR, EA, TGA, and the Br?nsted acidity was well determined by UV–vis. Among the ILs prepared, [EDA-PS][P-TSA] showed the highest catalytic activity for esterification due to its high acidity and appropriate miscibility with reactants, with an ultrahigh97.58% conversion of oleic acid under the optimum conditions(i.e. reaction time, 1.8 h;catalyst amount, 3 wt%;alcohol/acid molar ratio, 13:1,temperature 70℃) acquired from the Box–Behnken response surface methodology. With the novel strategy of multi –SO_(3) H modification on ILs,our catalyst had an approaching or even superior oleic acid conversion rate compared to other reported catalysts with considerably lower catalyst dosage and shorter reaction time. More importantly, it also exhibited high generality for converting various FFA feedstocks into biodiesel with considerable conversion within 93.59–94.33% under a rather lower catalyst dosage, which showed the valuable potential for converting low-cost oils into biodiesel from an economic and environmental perspective.